The present invention relates generally to pyrotechnic safety device disposal and more particularly to fail-safe automotive pyrotechnic safety device disposal.
Automotive vehicles typically contain a passive restraint system that includes a variety of pyrotechnic safety devices (PSD's) and an array of crash sensors. In the event of a vehicle crash, the PSD's are activated or deployed in response to signals received from the crash sensors in order to mitigate injury to vehicle occupants. Examples of PSD's include air bags, seat belt pretensioners, deployable roll bars, deployable knee bolsters, deployable anti-submarining devices, and “pop-up” pedestrian safety hoods.
At the end of a vehicle's useful life, a number of undeployed “live” PSD's may remain in the vehicle. Due to their pyrotechnic nature, government regulations in many countries prohibit the removal, storage, and reuse of PSD's for safety reasons. Recently, many governments have also implemented regulations prohibiting disposal of vehicles containing undeployed PSD's, and now require that all undeployed PSD's be deployed prior to disposal of the vehicle. One such regulation is embodied in the ISO 26021 draft protocol, which requires the vehicle's restraint system controller to receive and act upon PSD disposal commands from an external device.
Because the primary objective of an automatic restraint system is to mitigate injury to vehicle occupants during a crash, it is desirable to activate PSD's only in certain vehicle impact conditions, when a collision event is identified to be significant enough to cause injury to the occupant(s).
In order to prevent inadvertent or unwanted deployments of PSD's, automatic restraint system controllers are typically designed to be “fail-safe,” such that no single component of the system can fail in a way that would cause deployment current to flow to the PSD. Generally, this fail-safe configuration is achieved by arranging a plurality of independent impact sensors, evaluation logic circuits, and deployment control hardware to only allow deployment current to flow when each individual component achieves a predetermined deployment state. However, the fail-safe configuration of the automatic restraint system controllers make it difficult to manually dispose of PSD's safely prior to disposal of the vehicle because the predetermined deployment state is typically achieved by sensory input indicating a crash event.
Thus, typical restraint system architecture runs contrary to regulations such as the ISO 26021 draft protocol, which requires PSD disposal deployments to be controlled through a single communication port. In order to achieve deployment through a single communication port, the associated control logic essentially bypasses many of the automatic restraint system controller's built-in interlocks and redundancies, which may potentially introduce additional risk of inadvertent deployment into the system if the individual components' failure modes are not properly managed.
Therefore, a need presently exists for a fail-safe method and apparatus for disposing of a pyrotechnic safety device that is compliant with new government regulations, such as the ISO 26021 draft protocol.